Platform cannula for guiding the expansion of expandable bodies and method of use

ABSTRACT

This invention relates to devices, such as cannulas or needles, which are used for inserting expandable structures, such as medical balloons, into interior regions of a human or animal body, as well as methods for their use. In various embodiments, insertion devices described herein are capable of flaring at their tip to ease insertion and removal of expandable structures and reduce the risk of damaging such expandable structures during their insertion, inflation and removal. In other embodiments, insertion devices described herein are capable of directionally guiding and/or inhibiting expansion of an expandable structure within an interior region of an animal or human body to create optimally placed cavities for repair, augmentation and/or treatment of fractured and/or diseased bone.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a non-provisional of provisional applicationNo. 60/195,207, filed on Apr. 7, 2000, now abandoned.

FIELD OF THE INVENTION

This invention relates to an insertion device which is capable ofguiding expansion of an expandable structure towards or away from adesired direction and/or interior region of an animal or human body.This invention further relates to an insertion device for insertingexpandable structures, such as medical balloons, into an interior regionof a human or animal body, wherein the device is capable of expanding atthe tip. The present invention also relates to methods of using thedisclosed devices in the repair, augmentation and/or treatment offractured and/or diseased bone.

BACKGROUND OF THE INVENTION

Expandable structures, such as balloon dissectors and catheters, areused in various surgical procedures and for various rehabilitativepurposes in the medical arts. In angioplasty, balloon catheters arecommonly inserted into veins and arteries to expand blood vessels, mostcommonly to dilate and/or remove obstructions in the blood vessel (e.g.to remove constrictions blocking blood vessels which can cause a heartattack or stroke). Other types of surgical balloons have been used toaid surgeons in accessing specific organs during surgery, usually inlieu of previous insufflation techniques. Such balloons are commonlyinserted in a deflated state through an insertion device comprising acannula, catheter tube, or other similar device, and are positionedunder an organ. The balloon may then be inflated to lift and separate adesired organ away from surrounding organs and tissue to make sides ofthe desired organ easier to access during surgery. The balloon may alsobe placed and inflated so as to lift and separate other organs andtissues, leaving the desired organ for surgery exposed beneath.

Medical balloons have also been used during procedures for repairingand/or reinforcing fractured and/or diseased bones. Some physicians haveused such balloons to create a working space adjacent fractured and/ordiseased bone to allow the installation of plates, screws and/or otherimplantable articles to the bone. In this type of procedure, a cannulais generally inserted through an incision in the skin near the fracturearea. A balloon is then inserted through the cannula and inflatedbetween the bone and surrounding tissue around the fracture site tocreate a working space. A support plate and bone screws, or othersimilar implements, can then be installed at the fracture site throughsmall incisions in the skin. This type of procedure allows a surgeon toinstall implantable articles without having to make a long skin incisionto isolate and expose the bone.

More recently, balloons have been employed inside fractured and/ordiseased bones to repair, reinforce and/or treat the bone. In theseprocedures, balloons can be inserted through a cannula and inflatedinside the bone, which can compact cancellous bone, create a cavity andmove cortical bone. The cavity can be filled with a suitable bonefiller, such as bone cement (e.g., polymethylmethacrylate—PMMA),autograft or allograft tissue, or various other bone substitutes. Whenthe bone filler hardens, it essentially creates an internal “cast” whichallows the bone to heal properly, but also desirably allows the bone tobear weight immediately.

SUMMARY OF THE INVENTION

The present invention provides insertion devices which may be used withan expandable structure such as a balloon catheter to direct theexpansion of the structure toward or away from a desired direction.Directed expansion of the expandable structure provides the physicianwith significant control over the compression of cancellous bone andcreation of cavities within the bone, as well as control over themovement of cortical bone. In addition, the controlled expansion of anexpandable structure allows the physician to tailor the shape anddimensions of the cavity, and the resulting shape and dimensions of thebolus of filler material contained therein. Moreover, directed expansionof an expandable structure permits a physician to minimize disruption ofhealthy cancellous and/or cortical bone during a treatment procedure,thereby further enhancing healing of the bone after treatment.Accordingly, the devices and methods disclosed herein permit thephysician to optimize the ability of the bone to withstand compressiveforces and/or heal as quickly as possible after the procedure iscompleted.

Expandable structures such as balloon catheters and dissectors aretypically formed in spherical or elliptical shapes, and normally expandsubstantially outward. These balloons are desirably fairly low-profilesuch that they can fit through a cannula. Once inserted through thecannula into the region of treatment, such balloons will generallyinflate fairly symmetrically about the axis of the cannula or otherinsertion device. However, as discussed in U.S. Pat. No. 5,972,015,which is incorporated by reference herein, inflation of a balloon aboutthe cannula's axis can be undesirable in some situations. To account forthese situations, various alternative balloon designs and expansionconstraint arrangements have been proposed, such as those described inthe '015 patent.

The inventions disclosed herein further permit a practitioner to utilizea wide variety of expandable structures in conjunction with the methodsand devices disclosed herein. Because the cannula or other insertiondevice substantially guides the direction of expansion of the expandablestructure, there is less need to incorporate expansion constraints inthe expandable structure itself. In addition, if the insertion device iscomprised of a radiopaque material, the orientation of the device itselfcan be visualized during the surgical procedure under x-ray fluoroscopy,allowing the practitioner to visually verify the direction of expansionof the structure throughout the entire procedure. Of course, it shouldbe understood that the devices and methods of the present inventioncould also be used in conjunction with expandable structuresincorporating various expansion restraint arrangements.

In a general embodiment of the present invention, an insertion devicecomprises a hollow member, which is preferably cylindrical, with adistal end and a proximal end, wherein the distal end is the tip, orpoint of insertion, of the insertion device. The distal end of thehollow member desirably comprises a platform which constrains expansionof the expandable structure in one or more directions, but permits theexpandable structure to expand in non-constrained directions. In effect,the platform of the hollow member acts as a support or foundationagainst which the expandable structure pushes as it expands. Desirably,the supporting action of the platform induces the expandable structureto expand away from the platform, allowing the practitioner to directexpansion towards and/or away from a desired region.

In another general embodiment, the platform comprises a platform orexpansion guide which is inserted through a hollow member of aninsertion device, the guide desirably extending distally past the tip ofthe hollow member and into a bone. The guide will desirably act as asupport or foundation against which the expandable structure expands,inducing the structure to expand away from the guide. Because thisembodiment of the guide travels through the hollow member, and need notinitially penetrate soft tissues and/or the harder cortical bone, theguide design can be optimized to provide maximum support for theexpandable structure.

In another general embodiment of the present invention, an insertiondevice comprises a hollow member with a distal end and a proximal end,wherein the distal end is the tip, or point of insertion, of theinsertion device. The distal end of the hollow member desirablycomprises a platform which directs the expansion of the expandablestructure in one or more directions. The distal end of the hollow memberfurther comprises one or more crease or fold lines along which at leasta portion of the platform desirably deforms after insertion into a bone.By deforming along predetermined lines, sharp surfaces on the platformare desirably moved away from the expandable structure. In addition,bending of the platform can significantly affect the surface area of theplatform in contact with the expandable structure as well as thestrength and resistance to deformation of the platform. After theexpandable structure is contracted, the platform can be withdrawnthrough the cannula, with the distal end of the insertion devicedesirably bending the platform towards a lower-profile shape forremoval.

In another general embodiment of the present invention, the insertiondevice comprises a hollow member having a plurality of score linesspaced about the circumference of the distal tip, these score linesdesirably forming a plurality of adjacent sections oriented in a first,lower profile orientation. After inserted to a desired location withinthe vertebral body, the adjacent sections can be expanded outward to asecond orientation, where the adjacent sections substantially form afunnel, cone or flare at the tip of the insertion device. When removalof the expandable structure is desired, the flared tip desirably guidesthe expandable structure into the cannula, facilitating passage of theexpandable structure into and through the cannula. If desired, theadjacent sections can further incorporate one or more guides or ribswhich desirably impinge upon the expandable structure, folding and/ortwisting the expandable structure along desired lines and/or in adesired manner, further facilitating removal of the expandable structurethrough the cannula. When removal of the insertion device from thevertebral body is desired, the withdrawal of the insertion devicethrough the harder cortical bone desirably bends the adjacent sectionsback towards and/or into their first, lower profile orientation.

The present invention is further related to methods for using thedisclosed devices for repair, augmentation and/or treatment of fracturedand/or diseased bones. One embodiment of an insertion device constructedin accordance with the teachings of the present invention is insertedthrough cortical bone and into cancellous bone in a vertebral body of apatient. The insertion device is positioned such that the platformdirects the expansion of an expandable structure towards a section ofcortical bone to be moved to a desired position, such as a depressedupper or lower plate of a vertebral body. The expandable structure isexpanded against the platform, which desirably induces the expandablestructure to expand substantially away from the platform, compressingcancellous bone to form a cavity and moving the targeted section ofcortical body towards a desired position. The expandable structure iscontracted, and the cavity is then filled with an appropriate bonefiller material. This method, which permits manipulation of corticalbone with a minimum of cancellous bone compression, allows apractitioner to move targeted cortical bone while preserving much of thecancellous bone in an uncompressed state. In addition, this methodpermits the practitioner to maximize the force which the expandablestructure exerts on the cortical bone.

In another embodiment of the present invention, an insertion deviceconstructed in accordance with the teachings of the present invention isinserted into cancellous bone in a vertebral body of a patient. Theinsertion device is positioned such that the platform directs theexpansion of an expandable structure towards a section of cancellousbone to be compressed. The expandable structure is expanded, whichdesirably compresses some or all of the targeted cancellous bone,creating a cavity within the cancellous bone. The expandable structureis contracted and, if desired, the insertion device is repositioned suchthat the platform directs the expansion of an expandable structuretowards another section of cancellous bone to be compressed. Theexpandable structure is expanded, compressing some or all of thetargeted cancellous bone and increasing the size and/or altering theshape of the cavity within the bone. If desired, the procedure can berepeated to create a cavity of desired dimensions. The cavity is thenfilled with an appropriate bone filler material. This method, whichfacilitates the creation of large cavities within the bone, allows thepractitioner to tailor the cavity shape/size to optimize thepost-treatment strength and/or healing of the bone. Similarly, thedisclosed method can be used to reposition cortical bone towards adesired position, permitting a practitioner to gradually displace smallor large sections of the cortical bone, at the practitioner's option.

In another embodiment, the disclosed devices and methods facilitate apractitioner's ability to repair, reinforce and/or treat targeted boneregions in situations where the insertion device is initially positionednear a cortical bone wall of a targeted bone region. Because thedisclosed devices and methods provide substantial control over thedirection of expansion of the expandable structure, the practitioner canposition and/or reposition the platform to shield the nearby corticalbone from some or all of the expandable structure during some or all ofthe surgical procedure. Depending upon the orientation of the platform,the structure can be expanded to differing dimensions, desirablymaximizing compression of cancellous bone and/or movement of corticalbone at each orientation. Accordingly, there is no need to reorient theentire insertion device to accomplish the objectives of the procedure,which desirably eliminates a source of additional trauma occurringduring the procedure.

In another embodiment, an insertion device is inserted through corticalbone and into cancellous bone in a vertebral body of a patient. A styletin the insertion device is removed, causing the distal end of the hollowmember of the insertion device to expand or flare. An expandablestructure is inserted through the insertion device into the vertebra, isexpanded to create a cavity, and is contracted and removed through theinsertion device. As the expandable structure is withdrawn through theinsertion device, the flared distal end of the insertion devicedesirably guides the structure into the insertion device. The cavity isthen filled with an appropriate bone filler.

Other objects, advantages and embodiments of the invention are set forthin part in the description which follows, and in part, will be obviousfrom this description, or may be learned from the practice of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a coronal view of a vertebral body, showing a cannula insertedin a vertebral body, with a spherical expandable structure expandedwithin the vertebral body;

FIG. 2 is a coronal view of a vertebral body, showing one embodiment ofan insertion device constructed in accordance with the teachings of thepresent invention which has been inserted into a vertebral body, with anexpandable structure expanded within the vertebral body;

FIG. 3 a is a side view of an alternate embodiment of an insertiondevice constructed in accordance with the teachings of the presentinvention, wherein the distal end of the hollow member comprises one ormore longitudinal score lines at its circumference.

FIG. 3 b is a cross-sectional side view of the insertion device of FIG.3 a, showing the adjacent sections in a lower profile orientation;

FIG. 4 is a side view of the insertion device of FIG. 3 a, showing theadjacent sections in a deployed or flared position;

FIG. 5 is a cross-sectional side view of the insertion device of FIG. 3a, with a stylet positioned within the hollow member of the device;

FIG. 6 is an end of the insertion device of FIG. 4;

FIG. 7 is a side view of another alternate embodiment of an insertiondevice constructed in accordance with the teachings of the presentinvention, the device comprising an extension or platform extending fromthe distal end of the device;

FIG. 8 is a top plan view of another alternate embodiment of aninsertion device constructed in accordance with the teachings of thepresent invention, showing a crease line extending along a platform ofthe device;

FIG. 9 a is a side view of another alternate embodiment of an insertiondevice constructed in accordance with the teachings of the presentinvention with a stylet positioned within the lumen of the device;

FIG. 9 b is a cross sectional side view of the insertion device of FIG.9 a, showing the adjacent sections in a lower profile orientation;

FIG. 9 c is a side view of the insertion device of FIG. 9 a, showing theadjacent sections moved to a deployed position as the stylet iswithdrawn from the device;

FIG. 10 is an end view of another alternate embodiment of an insertiondevice constructed in accordance with an alternate embodiment of thepresent invention;

FIG. 11 is a side view of the insertion device of FIG. 10.

FIG. 12 is a side view of the insertion device of FIG. 10, with a styletpositioned within the hollow member of the device;

FIG. 13 is a side view of an alternate embodiment of an insertion deviceconstructed in accordance with the teachings of the present invention,with a stylet positioned within the hollow member of the device;

FIG. 14 is a side view of one embodiment of a stylet constructed inaccordance with the teachings of the present invention, for use withvarious embodiments of the insertion device of the present invention;

FIG. 15 is a side view of an alternate embodiment of a styletconstructed in accordance with the teachings of the present invention,for use with alternate embodiments of the insertion device of thepresent invention;

FIG. 16 a is a cross sectional side view of an alternate embodiment ofan insertion device and stylet constructed in accordance with theteachings of the present invention, showing one method of assembling thedevice and stylet;

FIG. 16 b is a cross section side view of the insertion device andstylet of FIG. 16 a, showing the stylet inserted fully into the hollowmember of the device during assembly;

FIG. 17 is a cross sectional side view of the insertion device andstylet of FIG. 16 b, with the adjacent sections of the device positionedin a lower profile orientation around the stylet;

FIG. 18 depicts a patient about to undergo a surgical procedure inaccordance with the teachings of the present invention;

FIG. 19 depicts an incision point and underlying vertebrae for thepatient of FIG. 18;

FIG. 20 is a corona view of a vertebra showing an insertion deviceapproaching the posterior side of the vertebral body;

FIG. 21 a depicts an insertion device penetrating the vertebral body ofFIG. 20;

FIG. 21 b is a coronal view of the vertebra of FIG. 20, with aninsertion device positioned within the cancellous bone;

FIG. 22 is a coronal view the vertebra body of FIG. 21 a, with theadjacent sections positioned in a deployed orientation.

FIG. 23 is a coronal view of the vertebra body of FIG. 22, wherein anexpandable structure is expanded within the vertebra;

FIG. 24 is a coronal view of a vertebra showing an insertion devicecomprising a platform within the vertebra, and an expandable structureexpanding away from the platform of the insertion device;

FIG. 25 is a coronal view of the vertebra of FIG. 24, wherein theexpandable structure has been contracted, the device rotated, and anexpandable structure expanded towards another region of the vertebra;

FIG. 26 is a coronal view of the vertebra of FIG. 24, wherein thecreated cavity is filled with a bone filler;

FIG. 27 is a coronal view of the vertebra of FIG. 24, wherein anexpandable structure and insertion device are used to enlarge a firstcavity which has been partially filled with a bone filler;

FIG. 28 are side and perspective views of various embodiments ofplatforms constructed in accordance with the teachings of the presentinvention;

FIG. 29 is a side perspective view of one embodiment of an expansionguide constructed in accordance with the teachings of the presentinvention;

FIG. 30 is a partial side perspective view of the expansion guide ofFIG. 29 inserted into an insertion device;

FIG. 31 is a side view of another alternate embodiment of an insertiondevice constructed in accordance with an alternate embodiment of thepresent invention;

FIG. 32 is a cross-sectional view of the insertion device of FIG. 31,taken along line 32-32;

FIG. 33 is a cross-sectional view of the insertion device of FIG. 31,taken along line 33-33;

FIG. 34 is a side view of another alternate embodiment of an insertiondevice constructed in accordance with an alternate embodiment of thepresent invention;

FIG. 35 is a cross-sectional view of the insertion device of FIG. 34,taken along line 35-35;

FIG. 36 is a cross-sectional view of the insertion device of FIG. 34,taken along line 36-36;

FIG. 37 is a cross-sectional view of a step in one method ofmanufacturing the insertion device of FIG. 34, taken along line 36-36;

FIG. 38 is a cross-sectional view of the insertion device of FIG. 37,during a subsequent manufacturing step;

FIG. 39 is a cross-sectional view of the insertion device of FIG. 37,during a subsequent manufacturing step.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention overcomes the problems and disadvantagesassociated with current strategies and designs in insertion devices foruse with expandable structures, such as medical balloons. In particular,the present invention provides insertion devices which may be used withexpandable structures to direct expansion of the structure as well as toassist in insertion and removal of expandable structures from aninterior region of a human or animal body. The methods and instrumentssuitable for such treatment are more fully described in U.S. Pat. Nos.4,969,888, 5,108,404, 5,827,289, 5,972,015, 6,048,346 and 6,066,154,each of which are incorporated herein by reference.

FIG. 1 depicts a vertebra 41 to be treated using an expandable structure310. An insertion device 200, such as a cannula or spinal needle,extends through the cortical bone 69 of the vertebra 41, and into thecancellous bone 71. An expandable structure 310 is introduced into thevertebra 41 through the insertion device 200, and desirably expandswithin the cancellous bone 71, typically expanding outward in aspherical, cylindrical or other manner thereby creating a cavity. Toavoid contacting the cortical bone 69 during expansion of the structure310, a practitioner will typically position the insertion device 200 asufficient distance away from the cortical bone 69 to allow room for thestructure 310 to expand outward. However, if the insertion device 200 ispositioned too close to the cortical bone 69, if the structure expands agreater amount towards the cortical bone 69 (such a where the cancellousbone is weaker in that direction), or if the intervening anatomyseverely constrains placement of the insertion device to locations nearthe cortical bone 69, the expansion of the structure and cavity creationmay be less than optimal.

FIGS. 2 and 7 depict one embodiment of an insertion device constructedin accordance with the teachings of the present invention. The insertiondevice comprises a hollow member 210 which may be any appropriate shape,but is preferably cylindrical. The hollow member 210 has a distal end250 and a proximal end 255, wherein the distal end 250 is the tip, orpoint of insertion, of the insertion device. The hollow member 210 maybe any appropriate length to allow the insertion device to providepercutaneous access to an interior region of a body requiring treatment.In one preferred embodiment, the hollow member 210 is approximately 12cm long.

The hollow member 210 has an appropriate central bore diameter and wallthickness to allow surgical instruments and/or medical materials to bepassed therethrough, while desirably being strong enough to resistdeformation during insertion into an interior region of a body such as abone. In a preferred embodiment, the hollow member 210 has an internalbore diameter of 0.3 cm and a wall thickness of 0.05 cm. The hollowmember 210 may further be made of any material which is appropriate foruse within a human or animal body including, but not limited to,stainless surgical steel, teflon, polyethylene, polypropylene,silicates, and liquid crystal polymers (as described in U.S. Pat. No.6,036,711, which is incorporated herein by reference). In one preferredembodiment, the hollow member 210 is made of stainless steel. Ifdesired, the hollow member 210 may further be coated with anyappropriate medical grade coating including, but not limited to, ananti-infective, an anticoagulant, a release coating, and/or a slippingagent.

In one embodiment, an extension or platform 220 protrudes from thedistal end 250 of the hollow member 210. In this embodiment, theplatform 220 comprises a semi-cylindrical section which extends from thewalls of the hollow member 210. Of course, the platform could be formedin many different configurations, including one or more of those shownin FIG. 28. In one preferred embodiment, the platform 220 is made of thesame material as the hollow member 210. Of course, it should beunderstood that the platform 220 could be formed of and/or coated withmaterials different from those incorporated into the hollow member 210.In addition, the platform 220 could be formed integrally with the hollowmember 210, such as by cutting away a portion of the hollow member 210near the distal tip 250 and leaving a cradle shape, or by attaching theplatform 220 to the distal tip 250 of the hollow member by various meanswell known in the art such as welding, adhesive bonding, etc. In oneembodiment, the platform 220 will have sufficient column strength suchthat it will not buckle and/or significantly deform as the insertiondevice is introduced through soft tissue and/or the bone. In thedisclosed embodiment, the portion of the distal tip 250 of the hollowmember 210 has been longitudinally bisected and removed, with theremaining semi-cylindrical section comprising the platform 220.

Desirably, the platform 220 will be positioned near the expandablestructure 310 prior to expansion, with the platform 220 located betweenthe expandable structure 310 and a region within the vertebra 41 whichis not to be compressed or affected. As the structure 310 expands, theplatform 220 will act as a support, foundation or barrier to theexpandable structure 310, inhibiting the structure 310 from expanding inone or more directions. In effect, the platform 220 will induce theexpandable structure 310 to expand away from the platform 220. Becausethe insertion device and platform 220 are substantially secured withinthe cortical bone, the platform 220 will desirably remain substantiallyrigid and/or immobile within the vertebra as the structure expands. Thisarrangement allows a practitioner to direct the expansion of theexpandable structure 310 towards or away from a specific region of thevertebra.

In another embodiment, best shown in FIG. 8, the platform 220 comprisesat least one longitudinal crease line 225, preferably located near thecenter of the platform, along which at least a portion of the platform220 desirably deforms prior to, during or after expansion of thestructure 310. By causing the platform 220 to deform in a controlledmanner, this embodiment facilitates introduction of the platform in alower profile condition, permits the platform to deform to a larger areato best direct the expansion of the structure, and then allows theplatform to be withdrawn in a lower profile condition. As an expandablestructure 310 is expanded, thereby exerting pressure against theplatform 220, the crease line 225 facilitates flattening of the platform220 in a controlled manner, thereby providing a widened and improvedsupport surface for guiding expansion of the expandable structure 310.Flattening of the support 220 can also deform outward the edges of theplatform 220, which may be sharp, thereby reducing the risk of damagingor rupturing the expandable structure 310. The crease lines 225 may becreated by mechanical cutting, laser etching, welding, brazing, or anyother well known means.

In an alternate embodiment, the crease line 225 could reinforce theplatform 220, minimizing deformation of the platform 220 duringexpansion of the structure 220. For example, the rounded underside ofthe platform 220 could be crimped or bent along the longitudinal axis ofthe platform to stiffen the platform 220 and resist deformation of thistype. If desired, the crimp (not shown) could parallel one or morecrease lines 225. In an alternate embodiment, a crimp (not shown) whichextends approximately 7 mm proximally from the distal tip of theplatform 220 results in a significant increase in the resistance of theplatform 220 to displacement and/or deformation.

In another alternative embodiment, the distal tip of the platformincorporates one or more serrations or teeth which extend outward fromthe distal tip and facilitate anchoring of the platform into theopposing cortical wall of the targeted bone region. This arrangement,which allows the platform to be supported at both ends, significantlyincreases the resistance of the platform to displacement and/ordeformation during expansion of the expandable structure.

In another embodiment, best shown in FIGS. 11, 12 and 13, the platform220 comprises a relatively flat section extending from the distal end250 of the hollow member 210. In a preferred embodiment, the platform220 can incorporate a flattened top surface 212 and a curved outersurface 213, the curved outer surface 213 being formed integrally withthe hollow member 210. Although this embodiment slightly constricts theinside bore of the hollow member 210, the shape and increased thicknessof the platform 220 greatly increase the amount of force the platform220 can withstand without deforming. In addition, this embodimentminimizes impingement of sharp edges onto the expandable structure.Moreover, the flat and thickened platform 220, as shown in FIG. 13, canbe shaped to have a sharpened tip so that the platform 220 can easilypass through soft tissue and/or bone. In an alternate embodiment, aflexible and/or pliable surface (not shown) may be positioned betweenthe expandable structure and/or the platform, or may be incorporatedinto the platform or expandable structure, to minimize tearing, cuttingand/or other failure of the expandable structure.

FIGS. 29 and 30 depict an alternate embodiment of an insertion deviceand associated component constructed in accordance with the teachings ofthe present invention. In this embodiment, the insertion device orcannula comprises a hollow member 210 which may be any appropriateshape, but is preferably cylindrical. The hollow member 210 has a distalend 250, wherein the distal end 250 is the tip, or point of insertion,of the insertion device. An expansion guide 400, best shown in FIG. 29,comprises a handle assembly 405 and a guide shaft 410. The guide shaft410 is desirably longer than hollow member 210, and is also desirablysized to pass through the lumen of the hollow member 210. In thedisclosed embodiment, an upper surface 420 of the guide shaft 410 isdesirably substantially flattened, and a lower surface 415 of the guideshaft is curved. If desired, the handle assembly 405 and/or guide shaft410 can incorporate one or more alignment marks 407 to indicate theorientation of the guide shaft, as well as the amount the guide shaftextends from the distal end 250 of the hollow member. In addition, thehandle assembly may incorporate mechanical connectors or clips (notshown) to secure the expansion guide 400 to the hollow member 210.

In this embodiment, after an insertion device is positioned within atargeted vertebral body, the expansion guide 400 can be positioned nearan expandable structure (not shown) prior to expansion, with the guideshaft 410 located between the expandable structure and an area of thecancellous bone where compression of the cancellous bone is not desired.If desired, the expandable structure can be introduced through theinsertion device before the expansion guide 400 is introduced throughthe insertion device. As the structure expands, the guide shaft 410 willact as a support, foundation or barrier to the expandable structure,desirably inhibiting the structure from expanding in one or moredirections. In effect, the guide shaft 410 will act similar to theplatform 220 previously described, and will induce the expandablestructure 310 to expand away from the guide shaft 410. This arrangementallows a practitioner to direct the expansion of the expandablestructure towards or away from a specific region of the vertebral body.In addition, because the expansion guide 400 can be inserted to varyingdepths within the hollow member, the practitioner can choose the desiredlength of the guide shaft 410 to extend out of the insertion device. Inan alternate embodiment, if desired a plurality of platforms (not shown)can be used to shield multiple directions.

Because the expansion guide 400 may be introduced after the insertiondevice is already positioned within the targeted vertebral body, theexpansion guide 400 need not have sufficient column strength topenetrate soft tissue and/or cortical bone. This allows the expansionguide 400 to assume a variety of cross sectional forms, including one ormore of the forms shown in FIG. 28.

In another alternate embodiment of an insertion device constructed inaccordance with the teachings of the present invention, best shown inFIGS. 3 a, 4 and 6, the insertion device comprises a cylindrical hollowmember 210 having a distal end 250 and a proximal end 255, wherein thedistal end 250 is the tip, or point of insertion, of the insertiondevice. The distal end 250 of the hollow member 210 is scoredlongitudinally to form a plurality of score lines 260 around thecircumference of the hollow member 210. The plurality of score lines 260may run parallel or at an angle to one another, and are separated byadjacent sections 265. The score lines 260 may be of any appropriatelength and depth to allow the distal end 250 to flare (See FIGS. 4 and6) when an outward pressure is exerted upon the adjacent sections 265.

In one preferred embodiment, the score lines 260 extend approximately0.5 cm along the longitudinal axis of the hollow member 210, and extendthrough the wall of the hollow member 210. The score lines 260 are cutinto the distal end 250 using any appropriate technique known to thoseof skill in the art including, but not limited to, laser cutting oretching, chemical etching and/or mechanical cutting with carbide ordiamond tip saws or high pressure water. The distal end 250 of thehollow member 210 will desirably comprise a sufficient number oflongitudinal score lines 260 to allow ease of flaring of the distal end250. The quantity of score lines 260 required for appropriate flaring isdetermined by the diameter and wall thickness of the hollow member 210and the ductility of the material. In one embodiment of the presentinvention, the hollow member 210 comprises at least three score lines260 in the distal end 250. In another embodiment, best shown in FIG. 6,the hollow member 210 comprises six score lines 260 in the distal end250.

The flaring of the tip of the hollow member 210 may ease insertion andremoval of an expandable structure, such as a medical balloon. Byflaring the tip, the sharp outer edges of the hollow member 210 arepushed away from the expandable structure and into the surroundingcancellous bone. The expandable structure is thus isolated from thesesharp edges, which could contact the expandable structure duringexpansion, possibly causing the structure to rupture or tear. Duringwithdrawal of the expandable structure, the larger diameter of theflared tip will desirably guide the expandable structure into thesmaller diameter hollow member 210, easing withdrawal of the expandablestructure into and through the hollow member 210.

If desired, flaring of the tip can be accomplished using an expandablestructure to provide a desired outward force, or the tip can be flaredmechanically. For example, in the embodiment shown in FIG. 3 b, theadjacent sections 265 are thickened on their internal surfaces to formone or more protrusions 266 extending inward from each adjacent section265. If desired, the protrusions 266 could be formed as a singlecontinuous thicker area of the circumference of distal end 250,interrupted by the longitudinal score lines 260. When a tool, such as ablunt obturator, boring member or stylet 275, which is described below,slides across or presses against the protrusions 266, the adjacentsections 265 are desirably forced outward, flaring the distal end 250 ofthe hollow member 210 in the desired manner.

The insertion device of the present invention may further comprise aremovable blunt obturator or stylet 275. See FIGS. 5, 9 a, 9 b, 12, and17. The stylet 275 comprises a distal end 279 having a tip 276 which canbe blunt or sharpened. If desired, the stylet can be cannulated (notshown) to accommodate the guide wire of a spinal needle assembly, aswell known in the art. In one embodiment of the present invention, bestshown in FIGS. 15, 16 a and 17, the tip 276 of the stylet 275 willdesirably extend from the distal end 250 of the hollow member 210 whenthe insertion device is assembled for insertion into an interior bodyregion. The stylet 275 desirably pushes and/or cuts a tunnel orpassageway through soft tissue and bone to permit placement of theinsertion device into the desired interior body region. If desired, thestylet 275 can further comprise a mating end (not shown) which allowsthe boring member 275 to be mated to the insertion device during theinsertion procedure, in a manner well known in the art. Mating of thehollow member 210 to the stylet 275 desirably prevents slippage andrelative movement between these devices during insertion into thepatient. The stylet 275 is preferably mated to the hollow member 210 ina manner which allows for easy removal of the stylet 275 from the hollowmember 210 after placement of the insertion device in the targeted area.

The stylet 275 may be made of any appropriate medical grade material andis preferably made of the same material as the hollow member 210. In onepreferred embodiment, the stylet 275 is made of stainless steel. Thestylet 275 may further be any appropriate shape and size which allows itto slide within and mate with the hollow member 210. In a preferredembodiment, the stylet 275 is approximately the same cylindrical shapeas the hollow member 210, is slightly longer than the hollow member 210so that the tip 276 will protrude from the distal end 250 of the hollowmember 210 when assembled for insertion, and is slightly smaller indiameter than the inner bore diameter of the hollow member 210, suchthat the stylet 275 can freely slide within the hollow member 210 foreasy insertion and withdrawal.

In one embodiment of the present invention, shown in FIGS. 15, 16 a, 16b and 17, the distal end 279 of the stylet 275 desirably comprises oneor more grooves or divots 273 located near the tip 276. In a preferredembodiment, the divot 273 is a continuous divot which encircles thecircumference of the distal end 279 of the stylet 275. A stylet 275having at least one divot 273 at the distal end 279 is well suited tomate with a hollow member 210 having a plurality of longitudinal scorelines 260 and one or more protrusions 266 on each adjacent section 265in its distal end 250, as depicted in FIGS. 3 b, 5, and 17. When such aninsertion device is assembled, the stylet 275 can be inserted into thehollow member 210 until the distal end 279 extends out of the hollowmember 210. The adjacent sections 265 are then folded or crimpedinwards, with the protrusions 266 extending into the divot 273 in thestylet 275, such that the outer wall of hollow member 210 is relativelycylindrical prior to insertion of the insertion device. Once theinsertion device is in place within the desired interior region of abody, the stylet 275 is pulled out of the hollow member 210, flaring theone or more protrusions 266 and forcing the distal end 279 of the stylet275 outward. In another embodiment, the collar section 267 adjacent toone or more protrusions 266 is thinner than the rest of the wall ofhollow member 210 to make flaring of the distal end 250 easier.

In another embodiment of an insertion device constructed in accordancewith the teachings of the present invention, best depicted in FIGS. 9 athrough 9 c, an insertion device comprises a hollow member 210 having aplatform 220 and one or more adjacent sections separated by a pluralityof longitudinal score lines 260 at the distal end 250. In anotherembodiment, this type of insertion device further comprises a stylet 275which has at least one divot 273 located near the tip 276. The stylet275 can be used to exert outward pressure on one or more protrusions 266on adjacent sections 265 causing the distal end 250 to flare out nearthe platform 220. Such a preferred embodiment of an insertion device ofthe present invention allows a user to direct expansion of an expandablestructure, such as a medical balloon, while easing insertion and removalof the expandable structure and reducing the risk of damage to theexpandable structure.

The present invention further provides methods for using the disclosedinsertion devices to direct expansion of the expandable structure and/orto simplify insertion and removal of an expandable structure from aninterior region of a human or animal body. For illustrative purposes, amethod for osteoporotic vertebral fixation, i.e. insertion and expansionin a vertebral body, will be described. However, a similar method may beused within any appropriate region of a human or animal body.

As shown in FIGS. 18-27, in one embodiment of the present invention, apatient 10 is placed onto a holder 15, generally U shaped, so that thepatient's back is exposed. An x-ray, CAT-scan, MRI, fluoroscope, orother appropriate device 20 which permits a practitioner to visualizethe insertion and placement of an insertion device during the surgicalprocedure may be positioned around the patient. An insertion device 200comprising a hollow member 210 fitted with a stylet 275, as previouslydescribed above, can be introduced through the soft tissues to avertebral body, which can located fluoroscopically. The stylet andinsertion device will desirably penetrate through the cortical bone 31of the vertebral body 30, and the stylet 275 can then be removed. In anembodiment of the insertion device wherein the hollow member 210comprises one or more adjacent sections 265 separated by a plurality oflongitudinal score lines 260, the removal of the stylet 275 desirablycauses the distal end 250 of the hollow member 210 to flare as depictedin FIG. 22.

An expandable structure 50, such as a medical balloon, can be insertedthrough the hollow member 210 into the vertebral body 30. Placement ofthe expandable structure 50 can be monitored by any appropriate means,including x-ray fluoroscopy or real time MRI. The structure is expanded,creating a cavity 55 within the cancellous bone 32 and/or movingcortical bone 31, and then contracted. In an embodiment where the distalend 250 of the hollow member 210 has been flared, the flared end guidesthe structure 50 into the hollow member 210. The cavity 55 can then befilled with an appropriate bone filler 60.

In another preferred embodiment of the present invention, the hollowmember 210 comprises a platform 220 extending from the distal end 250.See FIGS. 24 through 27. Once the hollow member 210 is introduced intothe vertebral body 30, the hollow member can be rotated until theplatform 220 shields an area of the vertebral body where expansion ofthe structure 50 is undesired. When the structure 50 is expanded, theplatform 220 induces the structure 50 to expand away from the platform220. In this way, an appropriate area for a cavity may be formedgenerally irrespectively of where the insertion device is placed withinthe vertebral body. Thus, if the insertion device is placed in aposition within the vertebral body that is not optimal for cavityformation, instead of torquing, bending, or otherwise adjusting theplacement of the entire insertion device, the insertion device 200 maysimply be rotated until the platform 220 faces a desired direction ofcavity formation. An indicator (not shown) on the handle or proximalportion of the hollow member 210 will desirably indicate to thepractitioner the orientation of the platform within the bone. Similarly,if a larger or asymmetrical cavity is desired, after a first cavity isformed by expanding the structure 50, the structure 50 may becontracted, the insertion device 200 may be rotated until the platform220 faces another direction, and the same or a different structure 50may be expanded to form a second cavity, etc., as depicted in FIG. 25.Any desired number and/or dimension of cavities may be formed in thisway. In another embodiment, different shaped balloons may be inserted toform each different cavity or multiple expandable structures of varyingshapes may be used to form each cavity.

When the desired cavity or cavities 55 have been formed, the expandablestructure 50 may be contracted and removed through the hollow member210. In an embodiment wherein the distal end 250 of the hollow member210 is flared, removal of the contracted structure may be easier becausethe flared tip guides the structure into the hollow member 210. Asuitable bone substitute, such as polymethylmethacrylate bone cement, atwo-part polyurethane material, or any other appropriate bone filler 60,is injected into the cavity 55 or cavities formed. In one embodiment, afirst cavity 55 may be formed and, if desired, at least partially filledwith a bone filler 60, then the same or a different expandable structure50 may be inserted and expanded in the same cavity 55, therebycompacting the hardening bone filler and/or more cancellous bone 32, andthe cavity 55 may then be further filled with the same or a differentbone filler 60. In another embodiment, a first cavity 55 may be formed,an insertion device 200 with a platform 220 may then be rotated and thesame or a different expandable structure 50 may be inserted to create asecond cavity or enlarge the first cavity 55, and the cavity(ies) maythen be filled with the same or a different bone filler 60. Thesemethods may be followed until all desired cavities have been formed andfilled.

Once all desired cavities have been filled, the insertion device 200 maybe removed from the vertebral body 30. The incision 25 may then bestitched closed and/or covered with bandages.

FIGS. 31-33 depict an alternate embodiment of an insertion device 600constructed in accordance with the teachings of the present invention.The insertion device 600 comprises a hollow member 620 and an expandablestructure 710. A handle 615 may be provided on the distal end of thehollow member 620 to facilitate manipulation of the tool and/orintroduction of a medium to expand the expandable structure 710. Thehollow member 620, desirably having a lumen 622 extending therethrough,comprises a shaft 624 and a distal tip 625. The distal end 625 of theshaft 624 can be rounded or beveled to facilitate passage throughcortical/cancellous bone, or can be or flattened to minimizeopportunities for penetrating the opposite cortical wall of the targetedbone region. An opening or window 700 is formed in the shaft 624, withan expandable structure 710 desirably positioned within the lumen 622 ata location adjacent the window 700. Upon introduction of the insertiondevice 600 into a targeted bone region (not shown), the expandablestructure 710 can be expanded (See FIGS. 33, P1 to P2 to P3), and atleast a portion of the expandable structure 710 will desirably expandthrough the window 700, thereby compressing cancellous bone, creating acavity and/or displacing cortical bone. Upon contraction of theexpandable structure 710, most of the expandable structure 710 willdesirably be drawn back into the lumen 622 for removal of the device 600from the vertebral body. If desired, the handle 615 and/or proximal end612 of the hollow member 620 can include markings (not shown) whichindicate the orientation of the window 700 within the targeted boneregion.

The expandable structure 710 may be comprised of a flexible materialcommon in medical device applications, including, but not limited to,plastics, polyethylene, mylar, rubber, nylon, polyurethane, metals orcomposite materials. Desirably, the shaft 624 will comprise a materialthat is more resistant to expansion than the material of the expandablestructure 710, including, but not limited to, stainless steel, ceramics,composite material and/or rigid plastics. In an alternate embodiment,similar materials for the expandable structure 710 and shaft 624 may beused, but in different thickness and/or amounts, thereby inducing theexpandable structure 710 to be more prone to expansion than the shaft624. The expandable structure 710 may be bonded directly to the shaft624 by various means well known in the art, including, but not limitedto, means such as welding, melting, gluing or the like. In alternativeembodiments, the expandable structure may be secured inside or outsideof the shaft 624, or a combination thereof. In at least one alternativeembodiment, at least a portion of the material comprising the expandablestructure 710 will plastically deform as it expands.

If desired, the shaft 624 may be sized to pass through the lumen of acannula or spinal access needle (not shown) already positioned withinthe targeted bone region. Alternatively, this embodiment of an insertiondevice 600 can be utilized without an associated insertion device. Insuch a case, the insertion device 600 will desirably incorporate asharpened distal tip 625 capable of penetrating the soft tissues andcortical/cancellous bone of the vertebral body. The distal tip may behollow or a solid construct, depending upon the desired penetrationstrength of the device 600. Similarly, the window 700 may extend aroundmore or less of the periphery of the shaft 624, depending upon the sizeand configuration of the expandable structure 710 and the desiredpenetration strength of the device. For example, where the window 700extends around approximately 25% of the shaft 624, the penetrationstrength of the device 600 will be significantly greater than where thewindow extends around approximately 75% of the shaft 624. If desired,the handle 615 can incorporate an impacting surface (not shown) tofacilitate the use of an orthopedic mallet in placing the device 600 ina targeted bone region. In an alternate embodiment, after creation ofthe cavity, the expandable structure can be removed from the hollowmember 600, allowing bone filler to be introduced into the cavitythrough the hollow member.

FIGS. 34 through 36 depict another alternate embodiment of an expansionguide 800 constructed in accordance with an alternate embodiment of thepresent invention. In this embodiment, the platform 810 comprises asemi-cylindrical section which extends from the walls of the hollowmember 820. A notch 825 extends longitudinally along the platform 810.The notch 825 will accommodate a key or projection of an expandablestructure (not shown), desirably securing the expandable structure tothe platform 810.

Depending on the quality and strength of the surrounding cancellousand/or cortical bone, as an expandable structure expands against theplatform 810, the structure can “slide off” the platform 810. In asimilar manner, rotation of the platform may displace the expandablestructure in an unwanted manner. Desirably, the notch 825 will securethe structure to the platform 810, preventing such occurrences. Inaddition, the structure may be contracted and the notch 825 used to drawthe expanding structure back into proper orientation with the platform810.

FIGS. 37 through 39 depict one method of manufacturing the platform 810of FIG. 34. In this embodiment, a distal end of the shaft 820 is cutalong a longitudinal line A. Alternatively, the shaft 820 may be cutalong longitudinal lines B, depending upon the desired size of the notchand the desired angles of the side walls of the notch. The shaft isplaced in a stamping machine 850 and a die 860 stamps the cut walls 821of the shaft 820 against the opposing walls 822 of the shaft 820.Desirably, the cut walls 821 will contact the opposing walls 822,thereby forming a notch 825 between by the cut walls 821 and theopposing wall 822.

In a similar manner, a notch could be formed in the embodiment of aninsertion device described in FIGS. 29 and 30, and used to guide andsecure an expandable body to the platform. Once positioned within thetargeted bone region, the platform could be manipulated and/or rotatedwith the expandable structure secured thereto. This embodiment wouldthereby greatly facilitate proper placement of the expandable structureon the platform in a desired orientation. If desired, the notch could beformed by molding, grinding, stamping or any other machining methodknown to those in the art.

While the disclosed devices and methods are more specifically describedin the context of the treatment of human vertebrae, other human oranimal bone types can be treated in the same or equivalent fashion. Byway of example, and not by limitation, the present systems and methodscould be used in any bone having bone marrow therein, including theradius, the humerus, the vertebrae, the femur, the tibia or thecalcaneous.

Other embodiments and uses of the invention will be apparent to thoseskilled in the art from consideration of the specification and practiceof the invention disclosed herein. All documents referenced herein arespecifically and entirely incorporated by reference. The specificationand examples should be considered exemplary only, with the true scopeand spirit of the invention being indicated by the following claims. Aswill be easily understood by those of ordinary skill in the art,variations and modifications of each of the disclosed embodiments,including combinations thereof, can be easily made within the scope ofthis invention as defined by the following claims.

1. A method comprising: providing a tool comprising a hollow bodyincluding a circumferential wall having a distal end, the tool alsocomprising an extension that protrudes from the circumferential wallbeyond the distal end and forms a platform that is open in a radialdirection to form a radial direction opening and in an axial directionto form an axial direction opening that is substantially transverse tothe radial direction opening, the platform having a side surface facingin the radial direction; providing an expandable structure; introducingthe tool and the expandable structure into a bone having an interiorvolume occupied, at least in part, by cancellous bone; positioning theplatform near the expandable structure, with the side surface of theplatform located between the expandable structure and a first region ofthe cancellous bone which is not to be compressed; securing theexpandable structure to the platform in a manner to maintain apredetermined rotational orientation between the expandable structureand the platform; forming a cavity in a second region of cancellous boneby expanding the expandable structure against the side surface of theplatform with the platform serving as a barrier to induce the expandablestructure to expand radially away from the side surface of the platformto compress the second region of the cancellous bone, while the firstregion of the cancellous bone remains substantially uncompressed, andintroducing a filler material into the cavity, wherein forming thecavity in the second region of cancellous bone includes expanding theexpandable structure in the axial direction through the axial directionopening of the platform such that the expandable structure expands inthe axial direction beyond a distal end of the platform.